The field of the invention is powder actuated tools and the invention relates more particularly to powder actuated tools for driving a fastener into concrete or steel. While several products are on the market for explosively driving fasteners, they have commonly been actuated by striking the upper end of the tool with a hammer. For many fastener locations, because of a cramped location, it is sometimes difficult to strike the end of the tool with a hammer.
Several high velocity twist actuated tools have been developed, one of which is shown in U.S. Pat. No. 2,760,401. A tool is shown in U.S. Pat. No. 2,679,645 which discloses a high velocity stud driving tool activated by the discharge of a cartridge. The cartridge is fired by the impact of a spring loaded firing pin released by the turning of a grip handle 11. As the tool is compressed against a work piece, a trigger or latch 48 engages a notch 54 of control cam 13. As the handle is turned, the control can 13 disengages the latch 48, releasing the firing pin carrier.
Another high velocity twist activated tool is shown in U.S. Pat. No. 2,787,000. In this instance, a firing pin is held by a sear-type trigger 51. When the trigger is released, the firing pin moves downwardly and strikes the cartridge.
These tools have several potential safety hazards. First of all, when a loaded tool is dropped, the trigger can be inadvertently released, discharging the cartridge and firing the fastener. Furthermore, the tool fires the fastener by classic bullet technology. That is, the discharge of the cartridge provides gases which fire the fastener out of a barrel very much in the same way that a bullet is fired by a cartridge. The result is a fastener which travels at a very high rate of speed and can actually pass through a wall board and maintain enough velocity to cause serious injury to someone standing on the other side of the wall board.
It is an object of the present invention to provide a low velocity powder actuated tool which is fired by twisting a handle and which cannot be fired by dropping.